1. Field of the Invention
This invention relates to ternary adhesives and systems formed from a branched polyester and two isocyanates, an isocyanate-capped polyester-urethane and a polyisocyanate. All of these are very soluble in organic solvents and can comply with pollution-abatement regulations. The adhesives contain aromatic groups and are particularly useful in bonding poly(ethylene terephthalate) to other flexible plastic substrates.
2. Prior Art
Bock et al. U.S. Pat. No. 3,584,075 shows a polyurethane adhesive based on an aliphatic polyester, an aromatic polyester, and a diisocyanate.
Schloss U.S. Pat. No. 3,666,835 shows textile laminating adhesives based on a hydroxyl-terminated urethane prepolymer and an isocyanate-terminated urethane prepolymer.
Fryd U.S. Pat. Nos. 3,763,079 and 3,804,810 show hydroxyl-terminated polyurethanes formed from copolyesters.
Yamazaki et al. U.S. Pat. No. 4,206,299 shows an adhesive for plastics and metal foil containing a silane coupling agent and acknowledges certain other prior art.
Sommerfeld et al. U.S. Pat. No. 4,298,724 (Sommerfeld) shows branched polyesters some of which are useful in this invention and procedures for making them applicable to all.
The above-identified art is incorporated herein by reference.